Resistors are common electronic devices utilized in integrated circuits. One known material for resistor fabrication is polysilicon. Polysilicon by itself is highly insulative. Conductivity enhancing impurities, such as for example boron or phosphorus, can be provided in polysilicon to render it conductive. The quantity of such impurities provided within a polysilicon layer will vary its conductivity. Accordingly, various resistors can be formed of polysilicon of a selected resistance depending upon impurity concentration.
This invention concerns a technique for increasing the resistance in a given polysilicon resistor construction apart from reducing impurity concentration.